Actuation System for a Lift Assisting Device and Roller Bearings Used Therein

ABSTRACT

An actuation system for deploying and retracting a lift assisting device of a wing of an aircraft, is presented. The actuation system includes a track pivotally coupled to the lift assisting device, a shaft rotating in response to flight control signals to deploy or retract the lift assisting device, means for actuating the lift assisting device between a retracted position and a deployed position along an arcuate path, a plurality of track roller bearings and a plurality of side roller bearings. The roller bearings rotatably contact the track to guide the track along the arcuate path. The track roller bearings are comprised of an outer ring, a split inner ring and liners disposed between bearing surfaces of the outer and the inner rings. The split inner ring is configured for accommodating deflection and bending of a mounting pin coupling the track roller bearing in proximity to the track.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional application of and claimspriority benefit under 35 U.S.C. §120 to U.S. patent application Ser.No. 12/201,062, filed Aug. 29, 2008, which is a U.S. Utility Applicationof U.S. Provisional Application Ser. No. 60/992,746, filed Dec. 6, 2007and to which priority benefit under 35 U.S.C. §119(e) is claimed, andboth of which are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to roller bearing assemblies for use in criticalapplications and, more particularly, to improved roller bearingassemblies used within an actuation system of an aircraft assembly.

2. Description of the Related Art

It is well known to use bearings to reduce friction between moving partsof a mechanical assembly. Similarly, it is well known to use bearingsthat roll on a fixed track to extend a first component from a secondcomponent. One implementation of such a track style bearing is within awing of an aircraft. For example, fixed wing aircraft typically includeslats movably arranged along a leading edge of each wing and flapsmovably arranged along a trailing edge of each wing. By selectivelyextending, retracting and deflecting the slats and flaps aerodynamicflow conditions on a wing are influenced so as to increase liftgenerated by the wing during takeoff or decrease lift during landing.For example, during take-off the leading edge slats are moved forward toextend an effective chord length of the wing and improve lift. Duringflight, the leading edge slats and trailing edge flaps are placed in aretracted position to optimize aerodynamic conditions.

Generally speaking, leading edge slat designs employ a series of rollerstyle bearings that guide fixed tracks to extend the leading edge slatsin order to increase lift at slow speed for landing and takeoff. Thetracks may have multiple configurations such as, for example, generalI-beam and PI-beam shapes. Since the tracks themselves are typically notoverly robust in their construction, multiple load conditions may berealized by the track roller bearings. Similarly, side load rollers orpins typically slide against the track to assist in centering the mainrollers on the track. The wing also includes actuation systems forpositioning the slats and flaps. Actuation systems include, for example,drive motors (e.g., hydraulic or electric drive motors), drive shaftsand other bearings such as spherical bearings, bushings and linkagebearings that assist in deployment and retraction of the slats andflaps. As can be appreciated, aircraft wing designs are beingcontinually developed as engineers seek to improve aircraft performancewhile increasing system capabilities. Newer designs are tending toincrease the number of systems employed within a wing cross section.Accordingly, space within the wing cross section is at a premium.Therefore, it is desirable to improve performance characteristics ofcomponents (e.g., to reduce maintenance) within the wing while alsominimizing space needed for such components.

Based on the foregoing, it is the general object of this invention toprovide an improved bearing for use in crucial applications.

SUMMARY OF THE INVENTION

The present invention resides in one aspect in an actuation system fordeploying and retracting a lift assisting device of a wing of anaircraft. The actuation system includes a track pivotally coupled to thelift assisting device, a shaft rotating in response to flight controlsignals to deploy or retract the lift assisting device, means foractuating the lift assisting device between a retracted position and adeployed position along an arcuate path, a plurality of track rollerbearings and a plurality of side roller bearings. The roller bearingsrotatably contact the track to guide the track along the arcuate path.In one embodiment, the track roller bearings are comprised of an outerring, a split inner ring and liners disposed between bearing surfaces ofthe outer and the inner rings. The split inner ring is configured foraccommodating deflection and bending of a mounting pin coupling thetrack roller bearing in proximity to the track. In another embodiment,the track roller bearings are comprised of an outer race, an inner raceand needle roller elements.

In one embodiment, the means for actuating includes a gear track coupledto the track and a pinion gear coupled to the shaft. The pinion gear hasgear teeth that engage the gear track. When the shaft rotates in a firstdirection the pinion gear engages the gear track to move the liftassisting device from the retracted to the deployed position along thearcuate path. When the shaft rotates in a second direction the piniongear engages the gear track to move the lift assisting device from thedeployed position to the retracted position along the arcuate path. Inanother embodiment, the means for actuating includes an actuator armcoupled to the track and an actuator lever coupled to the shaft and tothe actuator arm. When the shaft rotates in the first direction theactuator lever drives the actuator arm to move the track and the liftassisting device from the retracted to the deployed position along thearcuate path. When the shaft rotates in the second direction theactuator lever drives the actuator arm to move the track and the liftassisting device from the deployed position to the retracted positionalong the arcuate path.

In still another embodiment, each of the plurality of track rollerbearings are comprised of an outer ring having inner bearing surfaces,an inner split ring having a first portion and a second portion, each ofthe first and second portions having outer bearing surfaces, and aplurality of liners disposed between the inner bearing surfaces of theouter ring and the outer bearing surfaces of the inner ring. Each of theinner rings is comprised of 17-4PH steel and each of the outer rings iscomprised of AISI Type 422 stainless steel. In one embodiment, each ofthe outer rings is comprised of AISI Type 422 stainless steel with aspecial nitriding hardening process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a wing of an aircraft illustrating a pluralityof slat panels located at a leading edge of the wing;

FIG. 2 is a side cross-sectional view of the wing of FIG. 1 taken alongline 2-2 illustrating one of the slat panels in a deployed and aretracted position;

FIG. 3 is a front, partial cross-sectional view of a portion of the wingillustrating an actuation system for a slat panel, in accordance withone embodiment of the present invention;

FIG. 4 is a cross-sectional view of a track roller bearing in accordancewith one embodiment of the present invention;

FIG. 5 is a front, partial cross-sectional view of a portion of the wingillustrating side guide roller bearings in accordance with oneembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 provides a plan view of a leading edge section 12 of a wing 10 ofan aircraft 8. The wing 10 includes a plurality of slat panels 20deployed along the leading edge 12 of the wing 10. As described herein,an actuation system selectively extends and retracts the slat panels 20relative to the leading edge 12 in response to flight control signals,as is generally known in the art. FIG. 2 is a partial cross-sectionalview of the wing 10 taken along line 2-2 of FIG. 1 and illustrates oneof the leading edge slats 20 in a retracted position 20′ and in anextended position 20″. As shown in FIG. 2, in the retracted position(e.g., flight position) the slat 20′ is located against the leading edge12 of the wing 10 and in the deployed position (e.g., take-off andlanding position) the slat 20″ is deployed downwardly and forwardly awayfrom the leading edge portion 12 of the wing 10 thus increasing asurface area of the wing 10 to vary the wing's lift-enhancingcharacteristics.

An actuation system 40 of each slat 20 includes a track 50 extendingalong an arcuate axis A from a rear portion 52 to a forward portion 54.It should be appreciated that the track 50 may have multipleconfigurations such as, for example, an I-beam shape and a PI-beamshape. Generally speaking, webbing that constitutes support elements ofthe track is not overly robust. As such, multiple load conditions areexperienced at the track during operation that may be carried anddistributed by roller style bearings, as are described herein, to, forexample, the wing structure of the aircraft.

As shown in FIG. 2, the forward portion 54 of the track 50 is pivotallycoupled to an interior surface of the slat 20. In one embodiment, thetrack 50 is coupled to the slat 20 by means of, for example, linkagebearings 60. The actuation system 40 also includes an actuator lever 70.The actuator lever 70 is coupled to the track 50 via an actuator arm 80.The actuator lever 70 is also coupled to a shaft 90. As is generallyknown in the art, the shaft 90 extends along the leading edge section 12of the wing 10 and operates a plurality of actuator levers (similar tolever 70) coupled to respective ones of the plurality of slat panels 20in response to flight control commands to extend the slats when rotatingin a first direction and to retract the slats 20 when rotating in asecond direction.

A plurality of track roller bearings 100 are disposed about a firstouter surface 56 and a second outer surface 58 of the track 50. Thetrack roller bearings 100 are in rotational contact with the outersurfaces 56 and 58 of the track 50 to guide the track 50 in its arcuatepath along axis A during deployment and retraction. The path of travelof the slat 20 is illustrated in FIG. 2 by arrow B. As shown in FIG. 2,the plurality of track roller bearings 100 includes a first pair oftrack roller bearings 102 and 104 and a second pair of track rollerbearings 106 and 108. It should be appreciated that it is within thescope of the present invention to include more or less than theillustrated two pairs of roller bearings. For example, three rollerbearings may be disposed about one or both of the first outer surface 56and/or second outer surface 58 of the track 50. As described in detailbelow, it is also within the scope of the present invention for theplurality of track roller bearings 100 to include rolling element needlestyle track rollers or self lubricating style track rollers. In oneembodiment, a mounting web 110 encloses at least a portion of the track50. In one embodiment, the mounting web 110 extends into a fuel tankdisposed within the wing of the aircraft.

In one embodiment illustrated in FIG. 3, the actuation system 40includes a pinion gear 120 having teeth 122 that drive a gear track 130disposed within an interior portion 53 of the track 50. Preferably, thegear track 130 is positioned on a vertical centerline 55 of the track50. The pinion gear 120 is coupled to a shaft 124 (such as the shaft 90)that rotates in response to flight control commands. As the shaft 124and the pinion gear 120 rotate, a drive force is provided to the geartrack 130 for driving the track 50 along axis A between one of theretracted position 20′ and the extended position 20″ (FIG. 2). As shownin FIG. 3, the track roller bearing 100 is coupled to the mounting web110 about the track 50. For example, as shown in FIG. 3, the trackroller bearing 100 is coupled to the mounting web 110 above the track50.

As shown in FIG. 2, the plurality of track roller bearings 100 arecoupled to the mounting web 110 about the first and second outersurfaces 56 and 58 of the track 50 to support and guide the track 50during deployment and retraction. In one embodiment, illustrated in FIG.3, the track roller 100 is coupled to the mounting web 110 usingopposing bushings 140, a mounting pin 150 and a nut 160. In oneembodiment, the opposing bushings 140 are comprised of eccentricbushings and the nut 160 is comprised of a castellated nut to allowadjustment to the track 50 at fit-up. As shown in FIG. 3, the trackroller bearing 100 includes a plurality of needle roller elements 103(e.g., two rows of needle rollers in a double channel design). Theneedle roller elements 103 are lubricated with grease such as, forexample, Aeroshell 33, Mobil 28, Aerospec 200 or Aeroplex 444 as isrequired by predetermined maintenance procedures. In one embodiment, anouter ring 105, an inner ring and 107 and needle rollers 103 of thetrack roller bearings 100 are comprised of hardened stainless steel suchas, for example, 440C, 52100, 422 stainless with a special nitridingprocess (AeroCres®)(AEROCRES is registered trademark of RBC AircraftProducts, Inc., Oxford, Conn. USA), XD-15NW, and Cronidur 30.

In another embodiment, illustrated in FIG. 4, the track roller bearing100 is comprised of a lined track roller assembly 200 including an outerring 210 and an inner ring 220. The inner ring 220 is a split ringincluding a first portion 230 and a second portion 240. In oneembodiment, the first portion 230 and the second portion 240 includerespective body portions 232 and 242 as well as head portions 234 and244. The head portions 234 and 244 include flanges 236 and 246,respectively. In accordance with the present invention, the split ringconfiguration of the first portion 230 and the second portion 240 due totheir ability to deflect relative to one another, accommodate potentialdeflection and/or bending of the mounting pin 150 from stresses that maybe encountered during, for example, aircraft takeoff and landing. As canbe appreciated, unless accounted for a bending of the mounting pin 150may result in high friction or binding of the track roller 100 or 200and a failure to deploy or retract slats in response to flight controlcommands. The flanges 236 and 246 control axial motion of the outer ring210 to substantially eliminate contact of the outer ring 210 and theopposing bushings 140 utilized to mount the track roller 100 and 200within the mounting web 110.

As shown in FIG. 4, the lined track roller assembly 200 may also includeliners 250 disposed between bearing surfaces 212, 214 of the outer ring210 and bearing surfaces 222, 224, 226 and 228 of the inner ring 220. Inone embodiment, the liners 250 are constructed ofpolytetrafluoroethylene (commercially available under the designationTEFLON®)(TEFLON is a registered trademark of E.I. DuPont De Nemours andCompany, Wilmington, Del. USA), polyester, graphite, fabric impregnatedwith a polymer, urethane, polyimide, epoxy, phenolic or other type ofresin. In one embodiment, the liners 250 are molded and are comprised ofpolytetrafluoroethylene (TEFLON®), polyester, graphite, fibers in athermosetting composite resin made from polyester, urethane, polyimide,epoxy, phenolic or other type of resin. In one embodiment, the outerring 210 and the inner ring 220 is comprised of hardened stainless steelsuch as, for example, 440C, 52100, Custom 455®, Custom 465® (CUSTOM 455and CUSTOM 465 are registered trademarks of CRS Holdings, Inc.,Wilmington, Del., USA), and corrosion resistance steel such as 17-4PH,15-5PH and PH13-8Mo.

In one embodiment, the lined track roller assembly 200 also includesshields 260 and 270 disposed about shoulder portions 216 and 218 of anouter diameter of the outer ring 210 and extending to an outer diameter223 of the inner ring 220. The inventors have discovered that theshields 260 and 270 reduce friction and discourage dust and othercontaminates from entering and compromising contact between the bearingsurfaces 212, 214 of the outer ring 210 and bearing surfaces 222, 224,226 and 228 of the inner ring 220.

In one embodiment, illustrated in FIG. 5, a plurality of side guideroller bearings 300 are disposed about opposing sides of the track 50.The side guide roller bearings 300 are in rotational contact with theopposing side surfaces of the track 50 to guide the track 50, along withtrack roller bearings 100 and 200, in its arcuate path along axis Aduring deployment and retraction. In one embodiment, the plurality ofside guide roller bearings 300 are in rotational contact with wear padsaffixed to the track 50. In one embodiment, the plurality of side guideroller bearings 300 include needle roller bearings having outer races,inner races and needle rollers constructed of hardened stainless steelsuch as, for example, 440C, 52100, 422 stainless with a specialnitriding process (e.g., the aforementioned AeroCres® process), XD-15NW,and Cronidur 30. In yet another embodiment, the side guide rollerbearings 300 include end washers and seals. The end washers areconstructed of, for example, 52100 steel with cadmium plate or 420stainless steel. The seals are made from a thermoplastic such as, forexample, an acetal copolymer with lubricant fillers or Delrin®/Celcon®(DELRIN is a registered trademark of E.I. DuPont De Nemours and Company,Wilmington, Del. USA, and CELRON is a registered trademark of CNAHoldings, Inc., Summit, N.J. USA). The seals retain grease and preventof ingress dirt, dust and other contaminates into the bearings 300. Inone embodiment, needle roller elements of the bearings 300 arelubricated with grease such as, for example, Aeroshell 33, Mobil 28,Aerospec 200 or Aeroplex 444 as is required by predetermined maintenanceprocedures.

As described above, both the rolling element track bearings 100 and selflubricating track roller bearings 200 include a hard outer ring or raceto work in harmony with the mating track 50 that the bearings rollagainst. In one embodiment, the track 50 is comprised of titanium orsteel. In one embodiment, the track 50 may be coated with a materialsuch as, for example, tungsten carbide, although a coating is not arequirement of the present invention.

In addition to a unique bearing mounting configuration, another aspectof the present invention is related to the materials from which thebearings are manufactured. Historically, lined track bearings aremanufactured from relatively soft materials. For example, inner ringsare typically comprised of precipitation-hardening martensitic stainlesssteel such as, for example, 17-4PH steel, having a Rockwell hardness ina range of about HRc 30s to about HRc 40s, while outer rings aretypically comprised of precipitation-hardening stainless steel such as,for example, custom 455 steel, having a Rockwell hardness in the rangeof about HRc 40s. Outer rings may also be manufactured as throughhardened high strength steel having a Rockwell hardness of in the rangeof about HRc 50s to avoid flats that can occur. 440C steel has also beenused for outer rings. The inventors have discovered that, in certainapplications, it is beneficial to maintain inner rings manufactured from17-4PH steel, and that it is desirable to manufacture outer rings ofAISI Type 422 stainless steel. In one embodiment, each of the outerrings is comprised of AISI Type 422 stainless steel with a specialnitriding hardening process (e.g., the aforementioned AeroCres®process). Outer rings comprised of AISI Type 422 stainless steel withAeroCres® hardening are preferred for superior corrosion resistance andperformance as compared to conventional outer rings manufactured of 440Csteel.

Although the invention has been described with reference to particularembodiments thereof, it will be understood by one of ordinary skill inthe art, upon a reading and understanding of the foregoing disclosure,that numerous variations and alterations to the disclosed embodimentswill fall within the spirit and scope of this invention and of theappended claims.

1. An actuation system for deploying and retracting a lift assistingdevice of a wing of an aircraft, the actuation system comprising: atrack pivotally coupled to the lift assisting device, the track havingfirst and second outer surfaces and side surfaces; a shaft rotationallycoupled within the wing of the aircraft and operable, in response toflight control signals, to deploy or retract the lift assisting device;means for actuating the lift assisting device, coupled to the shaft,between a retracted position to a deployed position along an arcuatepath; a plurality of track roller bearings rotatably contacting thefirst and second outer surfaces of the track to guide the track alongthe arcuate path; and a plurality of side roller bearings rotatablycontacting at least one side of the track to guide the track along thearcuate path.
 2. The actuation system of claim 1, wherein the means foractuating is comprised of: a gear track coupled to the track; and apinion gear coupled to the shaft, the pinion gear having gear teeth thatengage the gear track; wherein when the shaft rotates in a firstdirection the pinion gear engages the gear track to move the liftassisting device from the retracted to the deployed position along thearcuate path, and when the shaft rotates in a second direction thepinion gear engages the gear track to move the lift assisting devicefrom the deployed position to the retracted position along the arcuatepath.
 3. The actuation system of claim 1, wherein the means foractuating is comprised of: an actuator arm coupled to the track; and anactuator lever coupled to the shaft and to the actuator arm; whereinwhen the shaft rotates in a first direction the actuator lever drivesthe actuator arm to move the track and the lift assisting device fromthe retracted to the deployed position along the arcuate path, and whenthe shaft rotates in a second direction the actuator lever drives theactuator arm to move the track and the lift assisting device from thedeployed position to the retracted position along the arcuate path. 4.The actuation system of claim 1, wherein the plurality of track rollerbearings includes at least one track roller bearing in rotationalcontact with an upper surface of the track and at least one track rollerbearing in rotational contact with a lower surface of the track.
 5. Theactuation system of claim 1, wherein the actuation system furtherincludes a mounting web enclosing at least a portion of the track andwherein the plurality of track roller bearings are coupled to themounting web.
 6. The actuation system of claim 5, wherein the trackroller bearings are coupled to the mounting web with opposing bushings,a mounting pin and a nut.
 7. The actuation system of claim 6, whereinthe opposing bushings are comprised of eccentric bushings and the nut iscomprised of a castellated nut to allow adjustment to the track atfit-up.
 8. The actuation system of claim 1, wherein the plurality oftrack roller bearings includes at least one track roller bearing havingneedle roller elements and at least one lined track roller assembly.